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Test Code PPGN2 TWO HOUR POST-PRANDIAL GLUCOSE SCREEN

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Grey Top, NaF/K-Oxalate

Other Acceptable specimens: N/A

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

  • Collect specimen per standard laboratory collection procedures. Collection to be followed in order as listed below.

Fasting Draw

A fasting glucose sample is collected from the patient in a grey top (fluoride) vacutainer tube prior to Glucocrush® 75 ingestion. The sample is labeled Fasting 

 

Stopping Point

  • GLUCOSE BEVERAGE INGESTION
    • Patients drinks the entire bottle of refrigerator-temperature Glucocrush© 75 solution from a paper cup within 5 minutes. The patient may pour the Glucocrush© 75 over ice if so desired. Timing begins the moment the patient starts drinking. Patient is to remain seated as much of the time as possible and is not to chew gum, smoke, drink or eat during the test.
  • PREPARE FOR BLOOD DRAW
    • Patient will return for blood draw no more than 55 minutes after the ingestion of the Glucocrush© 50 solution.
    • If the patient feels ill, or if she regurgitates, the phlebotomy staff should be notified immediately in order to contact the patient's physician for further instructions. If the physician instructs to have the test completed, this will be noted on the chemistry requisition.
  • DRAW/TUBE/TRANSPORT
    • Sample is drawn using a Gray Top Tube, exactly 60 minutes after the patient started drinking the Glucocrush© 50 solution. Sample tube is labeled "1 hr GDS" and sent immediately to Laboratory Service Center.

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Collect specimen per standard laboratory collection procedures. Collection to be followed in order as listed below.
  • GLUCOSE BEVERAGE INGESTION
    • Patients drinks the entire bottle of refrigerator-temperature Glucocrush© 50 solution from a paper cup within 5 minutes. The patient may pour the Glucocrush© 50 over ice if so desired. Timing begins the moment the patient starts drinking. Patient is to remain seated as much of the time as possible and is not to chew gum, smoke, drink or eat during the test.
  • PREPARE FOR BLOOD DRAW
    • Patient will return for blood draw no more than 55 minutes after the ingestion of the Glucocrush© 50 solution.
    • If the patient feels ill, or if she regurgitates, the phlebotomy staff should be notified immediately in order to contact the patient's physician for further instructions. If the physician instructs to have the test completed, this will be noted on the chemistry requisition.
  • DRAW/TUBE/TRANSPORT
    • Sample is drawn using a Gray Top Tube, exactly 60 minutes after the patient started drinking the Glucocrush© 75 solution. Sample tube is labeled "1 hr GDS" and sent immediately to Laboratory Service Center.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature within 2 hours of collection.
  • Aliquot removed plasma into a plastic tubes containing a minimum of 0.2 mL of specimen.
  • Plasma samples must then be sent room temperature at 20 - 25oC

 

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours

Reference Values

 

Test

Age

Sex

Reference Range

PPGF

All

All

< 100 mg/dL

PPGN

All

All

< 140 mg/dL

Critical Values

Analyte

Unit

Low

High

Age

Glucose

mg/dL

<40

>500

>14 days

CPT Codes

82947

LOINC Codes

N/A

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

3 days

Refrigerated

3 days

Frozen

N/A

Collection Instructions

  • Collect specimen per standard laboratory collection procedures. Collection to be followed in order as listed below.
  • GLUCOSE BEVERAGE INGESTION
    • Patients drinks the entire bottle of refrigerator-temperature Glucocrush© 50 solution from a paper cup within 5 minutes. The patient may pour the Glucocrush© 50 over ice if so desired. Timing begins the moment the patient starts drinking. Patient is to remain seated as much of the time as possible and is not to chew gum, smoke, drink or eat during the test.
  • PREPARE FOR BLOOD DRAW
    • Patient will return for blood draw no more than 55 minutes after the ingestion of the Glucocrush© 50 solution.
    • If the patient feels ill, or if she regurgitates, the phlebotomy staff should be notified immediately in order to contact the patient's physician for further instructions. If the physician instructs to have the test completed, this will be noted on the chemistry requisition.
  • DRAW/TUBE/TRANSPORT
    • Sample is drawn using a Gray Top Tube, exactly 60 minutes after the patient started drinking the Glucocrush© 50 solution. Sample tube is labeled "1 hr GDS" and sent immediately to Laboratory Service Center.

 

Test Components

Glucose

Clinical Indications

The GDS test is a screening test for possible diabetes in pregnant patients. Without regard to prior food intake, venous plasma glucose is measured, usually between 24 and 28 weeks of pregnancy, at an interval of one hour following an oral dose of 50 mg of glucose.

Methodology

Enzymatic Method with hexokinase (Roche Diagnostics)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • Interpretation of Results
    • Any result equal to or greater than 140 mg/dL, is considered abnormal. This level is recommended as a threshold to indicate the need for a full diagnostic glucose tolerance test, e.g. the Gestational GTT. The GDS should identify the majority of women with gestational diabetes mellitus (GDM), although some false negative may occur, especially in patients who are not fasting.

 

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: Not Available as STAT test

Routine Turnaround Time: up to 4 hours

Testing Schedule:  24/7

Synonyms/Keyword Search

GDS, DM, GDM, IFG, IGT

Last Review Date

1/26/23